Seating means for wood chipper bed knives



Sept. 4, 1951 c, A JOHNSON 2,566,938

SEATING MEANS FOR WOOD CHIPPER BED KNIVES Filed May 13, 1948 INVENTOR. C/mk/es /i J 11111;

ATTORNEY Patented Sept. 4., 1951 UNITED SEATING MEANS FOR WOOD CHIPPER BED KNIVES Charles A.'Johnson, Berlin, N. H. Application May 13, 1948, Serial No. 26,767

This invention relates to wood chippers for use in cutting wood into chips for the purpose of making paper. More particularly it concerns a new and improved wood chipping machine having a retractable, adjustable and self-seating bed knife.

Wood chippers generally comprise revolvable knife members mounted on a disk rotating in a vertical plane, a fixed horizontal bed knife having a cutting edge cooperating with the moving blades to cut the chips and an inclined feed spout to direct a piece of wood by gravity against the cutting members at a suitable angle. The running clearance between the revolving and stationary knives should remain substantially constant for all lengths of chips being out.

firmly anchored and arranged to form a continuation of the lower end portion of the feed spout so that the wood will be fed smoothly into the cutting knives without any catapulting effect by reason of the moving blades tending to rotate the piece of wood about the upper surface of the bed knife as a fulcrum and throw the same out of alinement with the inner surface of the spout, and to vary chip length by adjusting the ex- It has been the practice to provide a bed knife Claims. (Cl. 241-432) tension of the rotating knives from the disk and y,

shifting the latter axially toward and away from the stationary knife.

Because of the great strains to which the various parts of the machine are subject it is important that the bed knife be rugged and.

firmly seated in the main frame and not permitted to work loose or vibrate. Furthermore it should be maintained constantly in a sharpened condition so that chips will be cut evenly and smoothly without the production of slivers and irregular pieces which do not digest properly for paper making. In prior art machines it has been found that easily retractable or adjustable bed knives will be insecurely held, while if they are firmly anchored they will be removable for sharpening purposes only after virtually complete dismantling of the machine. Since the knife should be sharpened frequently the machine will be shut down for unreasonably long periods for this purpose, or the operators may be tempted to run the same for excessive periods using a dull blade, with consequent production of a high proportion of defective chips.

It is an object of the present invention to provide in a wood chipper a new and improved bed knife and seat therefor whereby the knife may be quickly and easily withdrawn and replaced without need for extensive dismantling of the entire machine.

A further object of the invention is to provide an improved and easily retractable b ed knife for a wood chipping machine in which the knife will be adjustable toward and away from the revolving knives as the latter are extended or retracted to vary chip lengths and nevertheless be firmly held in operative position. 1

Another object of the invention is to provide in a Wood chipping machine a. chipper knife base in which the knife will be self-seating and solidly held in proper spaced relation to the rotating cutting knives with the use of the minimum number of parts.

Further advantages and objects of the invention will become apparent from the following detailed description of a preferred embodiment thereof taken in connection with the accompanying drawings in which like numerals refer to like parts in several views and in which:

Fig. 1 is a front elevation of the novel wood chipping machine having a portion of the knifecarrying rotatable disc and one of the knives broken away to disclose the feed spout and .bed knife structure therebehind;

Fig. 2 is a sectional view on line '2--2 of Fig. 1;

Fig. 3 is a plan view of the bed knife of the invention removed from the machine;

Fig. 4 is an elevation of the same; and

Fig. 5 is a section on line 5-5 of Fig. 4.

The machine of the invention comprises essentially a fixed main supporting frame [0, a rotatable disc I2 mounted on a shaft [4 and suitably driven by a driving mechanism (not shown).

I The disc [2 carries four cutting knives l6 arranged adjacent corresponding slots iii to permit passage of the wood chips therethrough. A feed spout 20 is supported in part on thebase Ill by means of a supporting bracket 22 and is arranged at a suitableangle to feed the logs of wood against the rotating knives 16 in a manner well known in the art. The bracket 22 has a flat horizontal plate 24 adapted to be held firmly against the base plate 26 on the member If! by means of bolts 28.

As most clearly seen in Fig. 2, the base member I8 is also provided with a laterally extending slot 30, the bottom face 32 of which slopes downwardly and rearwardly to receive and support the bed knife 34 of the invention with its upper and lower shims 52 and 46 respectively, the function of which will hereinafter be more fully explained. It will be seen that the bed knife 34 is readily insertable through the side of the machine and will be held in fixed relation therein by the weight of the spout 2B.

face at an acute angle thereto to form a reentrant recess facing the path of the rotating knife, said surfaces being adapted to engage and solidly support a bed knife having bottom and back surfaces inclined to each other at the same acute angle as the angle of intersection of the corresponding surfaces of said seat when such bed knife is seated in said seat, whereby said bed knife may be adjusted toward the rotating knife solely by the insertion of shims between the bottom surface of the bed knife and said seating surface, and a spout assembly positioned on said base for holding said spout so that a portion of said assembly will rest on the upper surface of the bed knife when the latter is in seated position to subject the same to a vertical component of at least a portion of the weight of said spout to hold said bed knife firmly in said seat during chipping operations of said chipper.

3. Apparatus according to claim 2 in which said seating surface and said back wall surface extend laterally to a side wall of said base, thereby providing said re-entrant recess with an open end to permit insertion and withdrawal from seated position of said bed knife from one side of said base.

4. In a wood chipper having a rotating knife which cooperates with a stationary bed knife for chipping wood, the combination comprising: a stationary base, a bracket mounted on said base, an inclined feed spout held by said bracket for feeding logs into the path of the rotating knife, and a bed knife seat in said base, said seat comprising a downwardlly and rearwardly inclined seatingsurface and a back wall surface inclined upwardly and forwardly from the inner end of said seating surface at an acute angle thereto to form a re-entrant recess facing the path of the rotating knife, said surfaces being adapted to engage and solidly support a bed knife having bottom and back surfaces inclined to each other at the same acute angle as the angle of intersection of the corresponding surfaces of said seat when such bed knife is seated in said seat, whereby said bed knife may be adjusted toward the rotating knife solely by the insertion of shims between the bottom surface of the bed knife and said seating surface, said bracket being positioned on said base so that a portion thereof and the lower end portion of said spout will rest on portions of the upper surface of the bed knife when the latter is in seated position to subject the same to a vertical component of at least a portion of the weight of said spout to hold said bed knife firmly in said seat during chipping operations of said chipper.

5. Apparatus according to claim 4 in which said bracket is provided with jack screws bearing on said base for relieving the bed knife of the weight of said spout, and in which said seating surface and said back wall surface extend laterally to a side wall of said base, thereby providing said re-entrant recess with an open end to permit lateral insertion and withdrawal from seated position of said bed knife from. one side of said base while so relieved of said weight.

CHARLES A. JOHNSON.

REFERENCES CITED The following references are of record in the file of thispatent:

UNITED STATES PATENTS Number Name Date 467,786 Wigger Jan. 26, 1892 689,144 Thomas Dec. 17, 1901 1,185,155 Williams May 30, 1916 2,147,852 McDonald, Jr. et a1. Feb. 21, 1939 2,174,593 Pelot et a1 Oct. 3, 1939 2,299,248 Otterstand Oct. 20, 1942 2,420,966 Molz May 20, 1947 FOREIGN PATENTS Number Country Date 590,887 Germany Jan. 12, 1934 

